text-regex: add regex backend based on libtre

While memory consumption should be improved, backward searches
will still be slow, because they are implemented in terms of
repeated forward searches. It needs to be investigated whether
the underlying automaton can have its transitions reversed and
essentially run backwards, as is the case in sam.

1 files changed, 52 insertions, 0 deletions

diff --git a/configure b/configure
index dc8f278..fe85ccf 100755
--- a/configure
+++ b/configure
@@ -25,6 +25,7 @@ Fine tuning of the installation directories:
 Optional features:
   --enable-lua            build with Lua support [auto]
   --enable-lpeg           build with support for statically linking to LPeg [auto]
+  --enable-tre            build with TRE regex support [auto]
   --enable-selinux        build with SELinux support [auto]
   --enable-acl            build with POSIX ACL support [auto]
 
@@ -115,6 +116,7 @@ MANDIR='$(PREFIX)/share/man'
 
 lua=auto
 lpeg=auto
+tre=auto
 selinux=auto
 acl=auto
 
@@ -133,6 +135,8 @@ case "$arg" in
 --disable-lua|--enable-lua=no) lua=no ;;
 --enable-lpeg|--enable-lpeg=yes) lpeg=yes ;;
 --disable-lpeg|--enable-lpeg=no) lpeg=no ;;
+--enable-tre|--enable-tre=yes) tre=yes ;;
+--disable-tre|--enable-tre=no) tre=no ;;
 --enable-selinux|--enable-selinux=yes) selinux=yes ;;
 --disable-selinux|--enable-selinux=no) selinux=no ;;
 --enable-acl|--enable-acl=yes) acl=yes ;;
@@ -353,6 +357,50 @@ else
 	fail "$0: cannot find libtermkey"
 fi
 
+CONFIG_TRE=0
+REGEX_SRC=text-regex.c
+
+if test "$tre" != "no" ; then
+
+	printf "checking for libtre... "
+
+cat > "$tmpc" <<EOF
+#include <tre/tre.h>
+
+int main() {
+	regex_t preg;
+	tre_str_source *source = NULL;
+	regmatch_t pmatch[1];
+	tre_regcomp(&preg, "\0", REG_EXTENDED);
+	tre_reguexec(&preg, source, 1, pmatch, 0);
+	tre_regfree(&preg);
+	return 0;
+}
+EOF
+
+	if test "$have_pkgconfig" = "yes" ; then
+		CFLAGS_TRE=$(pkg-config --cflags tre 2>/dev/null)
+		LDFLAGS_TRE=$(pkg-config --libs tre 2>/dev/null)
+	fi
+
+	if test -z "$LDFLAGS_TRE"; then
+		CFLAGS_TRE=""
+		LDFLAGS_TRE="-ltre"
+	fi
+
+	if $CC $CFLAGS $CFLAGS_TRE "$tmpc" \
+		$LDFLAGS $LDFLAGS_TRE -o "$tmpo" >/dev/null 2>&1; then
+		CONFIG_TRE=1
+		REGEX_SRC=text-regex-tre.c
+		printf "%s\n" "yes"
+	else
+		printf "%s\n" "no"
+		CFLAGS_TRE=""
+		LDFLAGS_TRE=""
+		test "$tre" = "yes" && fail "$0: cannot find libtre"
+	fi
+fi
+
 CONFIG_LUA=0
 
 # enabling builtin lpeg requires lua support
@@ -537,6 +585,10 @@ CFLAGS_CURSES = $CFLAGS_CURSES
 LDFLAGS_CURSES = $LDFLAGS_CURSES
 CFLAGS_TERMKEY = $CFLAGS_TERMKEY
 LDFLAGS_TERMKEY = $LDFLAGS_TERMKEY
+REGEX_SRC = $REGEX_SRC
+CONFIG_TRE = $CONFIG_TRE
+CFLAGS_TRE = $CFLAGS_TRE
+LDFLAGS_TRE = $LDFLAGS_TRE
 CONFIG_LUA = $CONFIG_LUA
 CFLAGS_LUA = $CFLAGS_LUA
 LDFLAGS_LUA = $LDFLAGS_LUA